Vulcanized rubber for heat resistant vibration-isolators

Abstract: The present invention provides a vulcanized rubber useful for heat resistant vibration-isolator which can be obtained by vulcanizing a composition comprising: (A) 110-175 parts by weight of an oil-extended copolymer comprising 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber with an intrinsic viscosity [η] of 3 dl/g or more and 10-75 parts by weight of an extender oil; (B) 5-20 parts by weight of a liquid diene polymer with melt viscosity of 100-3000 poises at 25 °C, per 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber; and (C) 10-80 parts by weight of a reinforcing filler, per 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber; with an organic peroxide. The vulcanized rubbers of the present invention have an excellent thermal stability and durability, a low dynamic spring constant, and an excellent processability; they are useful for heat resistant vibration-isolator rubber, and are most suitable for, for example, uses of vibration-isolator for automobiles for engine mount, strato mount, suspension bush, exhaust mount and the like, and uses of vibration-isolator for vehicles for railway, vehicles for construction, industrial instruments, and instruments for office-automation and the like.

Description: The present invention relates to a vulcanized rubber useful for a heat resistant vibration-isolator which has an excellent durability and processability, and a low dynamic spring constant. Superior characteristics in durability, thermal stability and dynamic spring constant are required for a vibration-isolator rubber to be widely used in the automobile field. The dynamic spring constant is the extent of the change of elastic modulus (dynamic shear modulus of elasticity) at a high-frequency vibration and is represented by the ratio of dynamic shear modulus of elasticity and static shear modulus of elasticity. A dynamic spring constant is usually larger than 1, the lower the dynamic spring constant is, the superior the vibration-isolator property has. Hitherto, it has been well known that ethylene-α-olefin-non-conjugated diene copolymer rubber is used as rubber material for the vibration-isolator rubbers, but that this copolymer is inferior in durability although it is superior in thermal stability. On the other hand, the vulcanized rubber with a high molecular weight polymer ( its intrinsic viscosity [η] measured at 70°C in xylene is usually 2.5 dl/g or more) shows an improved durability, but it is not satisfactory from a point of a dynamic spring constant, but, it still has a problem that in the processing before vulcanization, there is apt to be generated the so-called bagging wherein a rubber composition rises to the surface of a roller at roll processing. When a softener or carbon black is added in large amounts to the high molecular weight polymer in order to improve the processability, the dynamic spring constant of the resulting rubber increases and hence its vibration-isolator property becomes inferior. The vulcanized rubber obtained from a rubber composition which comprises ethylene-α-olefin-non-conjugated diene copolymer rubber and hydrogenated liquid diene polymer (JP-B-3-73584 (1991)) is excellent in processability, but suffers from a poor dynamic spring constant. With a view to improve both the processability and vibration-isolator property of a vulcanized rubber, there has been proposed in JP-A-53-22551 (1978) that a low molecular weight EPDM is blended with a high molecular weight EPDM. But, in this method, the dynamic spring constant of the resulting rubber is not satisfactory though the processability and durability can surely be improved. In this method, vulcanized rubbers with an excellent durability and processability, and a low dynamic spring constant can hardly be obtained. US-A-4 803 020 discloses a method for the preparation of EPDM roof sheeting by ionizing radiation curing. A rubber composition for engine mounts made of ethylene-α-olefin-diene rubber is described in Database WPI, Week 9318 (AN 93-149331). The object of the present invention is to provide a vulcanized rubber useful for heat resistant vibration-isolators with a superior durability, a low dynamic spring constant, excellent thermal stability, and excellent processability. This object is solved by the present rubber composition comprising a copolymer rubber having a particular intrinsic viscosity and a liquid diene polymer having a particular melt viscosity which are vulcanized with an organic peroxide. In particular, the present invention provides a vulcanized rubber useful for heat resistant vibration-isolators which can be obtained by vulcanizing a composition comprising: (A) 110-175 parts by weight of an oil-extended copolymer comprising 100 parts by weight of an ethylene-a-olefin-non-conjugated diene copolymer rubber with an intrinsic viscosity [η] of 3 dl/g or more and 10-75 parts by weight of an extender oil; (B) 5-20 parts by weight of a liquid diene polymer with melt viscosity of 10-300 Pa·s (100-3000 poises) at 25 °C, per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber; and (C) 10-80 parts by weight of a reinforcing filler, per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber; with an organic peroxide. In the vulcanized rubber for heat resistant vibration-isolator of the present invention, an ethylene-a-olefin-non-conjugated diene copolymer rubber is used as basic rubber material , and the preferred mole ratio of ethylene/α-olefin of the copolymer rubber is usually 60/40-80/20 from a view point of a dynamic spring constant dependancy on temperature. The amount of the non-conjugated diene component in the copolymer rubber is preferably 0.5∼3 mole % of the total monomers composing the copolymer rubber from a view point of thermal stability and vibration-isolator property of the vulcanized rubber. In order that the said vulcanized rubber has an excellent durability, the intrinsic viscosity [η] of the said copolymer rubber must be 3 dl/g or more, preferably 3-5 dl/g, and more preferably 3.2-5 dl/g. The intrinsic viscosity [η] value when mentioned in the present specification means the value measured in xylene solution at 70 °C unless otherwise is indicated. For the ethylene-α-olefin-non-conjugated diene copolymer rubbers, propylene, 1-butene and 1-hexene are used as the α-olefins, and as the non-conjugated dienes, 1,4-pentadiene, 1,4-hexadiene, divinyl benzene, dicyclopentadiene, methylene norbornene, ethylidene norbornene ( hereinafter, abbreviated as ENB ) and vinyl norbornene are used. The ethylene-α-olefin-non-conjugated diene copolymer rubbers derived from these monomers may be used alone or in combinations thereof. In the present invention, the oil-extended ethylene-α-olefin-non-conjugated diene copolymer rubber is used to improve the processability of the non-vulcanized rubber composition. As the extender oil, paraffin processing oil is preferably used. The oil used in such amount that its addition makes the Mooney viscosity ML 1 + 4 121°C of the resulting oil-extended ethylene-α-olefin-non-conjugated diene copolymer rubber to about 60-120. Specifically, the usual amount of the extender oil is 10-75 parts by weight per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber, preferably 30-75 parts by weight. The extender oil is added to the ethylene-α-olefin-non-conjugated diene copolymer rubber to give the oil-extended copolymer rubber. The process oil may further be added to the rubber composition before the vulcanization. In the present invention, an oil-extended ethylene-α-olefin-non-conjugated diene copolymer rubber which contains a reinforcing filler is used to improve the static property and dynamic spring constant of the vulcanized rubber. As the reinforcing fillers, for example, carbon black and silica are used, especially carbon black is preferred. The amount of the reinforcing filler is usually 10-80 parts by weight, and preferably - in consideration of a dynamic spring constant- 30-70 parts by weight per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber. In the present invention, a liquid diene polymer is blended with the above-mentioned oil-extended ethylene-α-olefin-non-conjugated diene copolymer rubber for improving the vibration-isolator property by lowering the dynamic spring constant. The liquid diene polymer used in the present invention is a homo-polymer of 1,3-butadiene derivatives such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, butadiene glycol and butadiene di-carboxylic acid, or a copolymer of these 1,3-butadiene derivatives with other polymerizable monomers such as styrene, or their modified polymers. For example, polybutadiene, polyisoprene, poly 2,3-dimethyl-1,3-butadiene, polybutadieneglycol, polybutadiene dicarboxylic acid, can be used in the present invention. The liquid diene polymers having a high iodine value are preferred, especially those having a iodine value greater than 300 and less than 600. The liquid diene polymer used in the present invention has a melt viscosity of 10-300 Pa·s (100-3,000 poises) at 25 °C, preferably 20-250 Pa·s (200-2,500 poises), more preferably 20-200 Pa·s (200-2,000 poises) and most preferably 20-150 Pa·s (200-1,500 poises). Among these liquid diene polymers, a liquid polybutadiene or a liquid polyisoprene is preferably used, especially a liquid polybutadiene with melt viscosity of 20-100 Pa·s (200-1,000 poises) at 25°C or a liquid polyisoprene with melt viscosity of 20-150 Pa·s (200-1,500 poises) at 25 °C is preferred. It is usually preferable to use 5-20 parts by weight of the liquid diene polymers per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber from a view point of improving the dynamic spring constant and tensile strength of the rubbers. The vulcanized rubber for heat resistant vibration-isolator of the present invention is obtained by vulcanizing a rubber composition comprising the oil-extended ethylne-α-olefin-non-conjugated diene copolymer rubbers which contains a reinforcing filler and the above-mentioned specified amount of the liquid diene polymer as an essential component. It is very important that the vulcanization of the composition of the present invention is carried out with an organic peroxide, and vulcanized rubbers obtained by other vulcanization methods such as sulfur curing is inferior in thermal stability and other properties. As the organic peroxides, for example, dicumyl peroxide, di-tert butyl peroxide, tert-butyl cumylperoxide, 1,1-di( tert-butyl peroxy ) -3,3,5-trimethylcyclohexane, benzoylperoxide, lauroylperoxide are used in the present invention. The amount of the organic peroxide is 0.5-10 parts by weight, preferably 2-5 parts by weight, per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber. The vulcanized rubbers for heat resistant vibration-isolator of the present invention may contain additives which are usually used in this field such as zinc oxide, stearic acid, a softner, an antioxidant, an oxidation inhibitor, a process oil, a processing activating agent or a crosslinking coagent. As the crosslinking coagent used in the invention, sulfur, p-quinonedioxime, p,p-dibenzoylquinonedioxime, ethyleneglycol dimethacrylate and triallylisocyanurate are mentioned. The amount of crosslinking coagent is usually 0.5-2 parts by weight, but the amount of sulfur must be 0.5 part or less, per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber. The vulcanized rubbers of the present invention may contain a small amount of other rubber components than the ethylene-α-olefin-non-conjugated diene copolymer rubber such as natural rubber and styrene-butadiene rubber to adjust the adhesive property. The vulcanized rubbers for heat resistant vibration-isolator of the present invention can be produced by kneading the oil-extended ethylene-α-olefin-non-conjugated diene copolymer rubber with the reinforcing filler, the liquid diene polymer, organic peroxide and, if necessary, various additives, using therefor an instrument conventionally used for the production of rubber products such as Banbury mixer or open roll under the conventional conditions, then, vulcanizing at a temperature, for example, not lower than about 120°C, preferably between 150°C and 220°C for 1-30 min. using an instrument conventionally used in the organic peroxide vulcanization of rubbers such as injection machine or press. The vulcanized rubbers for heat resistant vibration-isolator of the present invention have a superior thermal stability and an excellent durability, a low dynamic spring constant, and an excellent processability. In the following examples, the compression sets- the indication of the thermal stability- of samples were measured by heat-treating a sample at 120 °C for 70 hours in a Geer oven according to JIS K6301. The compression sets of vulcanized rubbers of the present invention were found to be as good as 20% or less. The durability of samples were measured by heat-treating test pieces at 120 °C for 70 hours by a fatigue tester (Fatigue to Failure Tester of Monsanto Company Ltd.) repeatedly at 140% elongation ratio at room temperature and counting the elongation cycle numbers until breakage. The durability of vulcanized rubbers of the present invention is excellent, elongation cycle number is 200,000 or more. The dynamic spring constant was indicated as Ed/Es wherein the static shear modulus of elasticity Es ( Es = Gs x 3) was calculated from the static shear modulus Gs which was obtained on the basis of JIS K6386 and dynamic shear modulus of elasticity Ed which was measured at 23°C by vibration frequency of 100 Hz and vibration width ±0.1% by Rheovibron ( manufactured by Orientec Company Ltd.). A lower dynamic spring constant is preferable for vibration-isolator property. The dynamic spring constant of vulcanized rubbers of the present invention is excellent, the value is less than 1.9. Thus, the vulcanized rubbers of the present invention have a superior thermal stability and an excellent durability, a low dynamic spring constant, and an excellent processability. They are useful for the vulcanized rubbers of the heat resistant vibration-isolators, and are most suitable for, for example, uses of vibration-isolator for automobiles for engine mount, strato mount, suspension bush and exhaust mountings, and uses of vibration-isolator for vehicles for railway, vehicles for construction, industrial instruments, and instruments for office-automation. Examples The melt viscosity was measured under condition as follows. Instrument: RSM-800 RDS II manufactured by Rheometrix Company Ltd. Measuring tool: Pararell plate with diameter of 25 mm. Measuring temperature: 25 °C Strain: 0.5 % Frequency: 2π radian/sec. Example 1 . In a 1.7 1 BR type Banbury mixer, 140 parts by weight of oil-extended copolymer rubber (1) (40 parts by weight of parafin processing oil per 100 parts by weight of ethylene-propylene-ENB copolymer rubber which has an intrinsic viscosity [η] of 3.3 dl/g measured at 70 °C in xylene, an ethylene/propylene ratio of 70/30 and an ENB ratio of 1.2 mole % was blended and the Mooney viscosity ML 1 + 4 121°C was adjusted to 96), 10 parts by weight of NISSEKI Polybutadiene B3000 ( manufactured by Nippon Petrochemical Company Ltd. : liquid polybutadiene with a melt viscosity of 50 Pa·s (500 poises) at 25 °C), 70 parts by weight of FEF carbon black, 20 parts by weight of paraffin processing oil, 5 parts by weight of zinc oxide and 1 part by weight of stearic acid were added and kneaded, and the rubber composition was obtained. The rubber composition was transferred to a 10 inches open roll whose roll temperature was 60 °C and kneaded. The procesability (bagging was generated or not) and the skin condition of sheet were observed. The results are shown in Table 1. After the roll temperature was dropped to 40°C, 5 parts by weight of organic peroxide ( Sunperox DCP-98 manufactured by Sanken-kakou Company Ltd.) as a vulcanizer and 0.3 parts by weight of sulfur as a vulcanization activating agent per 100 parts by weight of the ethylene-propylene-ENB copolymer rubber were added and kneaded. The vulcanizing rubber composition obtained was heated at 170 °C for 20 minutes by heating-press and vulcanized sheets with 2 mm thickness were produced. Dynamic spring constant, heat stability (Compression set), and durability of the vulcanized rubber sheet obtained were measured. The results are shown in table 1. Regarding estimation of the processability (bagging was generated or not), no bagging was represented as ┌○┘, and a bagging generated was represented as ┌×┘, in the case of a 2.5 mm roll gap. Regarding the skin condition of sheet, the skin with flatness and no hole was represented as ┌○┘, and that with roughness and a hole generated was represented as ┌×┘. Example 2 and Comparative examples 1 to 6. Rubber compositions were prepared and vulcanized under the various blending conditons illustrated in table 1 according to the method of example 1 and vulcanized sheets were produced. The characteristics of the rubber compositions and the properties of each vulcanized rubber sheet are shown in table 1. Example 3. In 1.7 l BR type Banbury mixer, 140 parts by weight of the same oil-extended copolymer rubber (1) used in example 1, 10 parts by weight of Nisseki Polybutadiene B3000, 50 parts by weight of MAF carbon black, 5 parts by weight of zinc oxide, and 1 part by weight of stearic acid were added and kneaded, and a rubber composition was obtained. Vulcanized rubber sheets with a thickness of 2 mm were made from the obtained rubber composition as in example 1. The properties of each rubber composition and the characteristics of each rubber sheet are shown in table 2. Example 4, Comparative Example 7. A rubber composition was prepared under various blending conditions indicated in table 2 according to the method of example 3, and vulcanized, and vulcanized rubber sheets were made. The properties of each rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 2. Example 5. A rubber composition was prepared according to example 3, except using the oil-extended copolymer rubber (2) [40 parts by weight of parafin processing oil per 100 parts by weight of ethylene-propylene-ENB copolymer rubber which has an intrinsic viscosity [η] of 3.1 dl/g measured at 70°C in xylene, an ethylene/propylene ratio of 65/35 and an ENB ratio of 1.3 mole % was blended and Mooney viscosity ML 1 + 4 121°C was adjusted to 78 ), instead of the oil-extended copolymer rubber (1), and vulcanized, and vulcanized rubber sheets were made. The properties of the rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 2. Example 6, Comparative Example 8. A rubber composition was prepared under various blending conditions shown in table 2 according to the method of example 5 and vulcanized, and vulcanized rubber sheets were made. The properties of each rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 2. Comparative Examples 9, 10. A rubber composition was prepared according to the method of example 1 under the blending condition shown in table 3, by using the oil-extended copolymer rubber (3) [40 parts by weight of parafin processing oil per 100 parts by weight of ethylene-propylene-ENB copolymer rubber having an intrinsic viscosity [η] of 2.7 dl/g measured at 70°C in xylene, an ethylene/propylene ratio of 77/23 and an ENB ratio of 1.3 mole % was blended and Mooney viscosity ML 1 + 4 121°C was adjusted as 57), and vulcanized, and vulcanized rubber sheets were made. The properties of the rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 3. Comparative Examples 11, 12. A rubber composition was prepared under various blending conditions shown in table 3 according to the method of example 1 and vulcanized, and vulcanized rubber sheets were made. The properties of each rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 3. Example 7, Comparative Examples 13 to 15. A rubber composition was prepared under various blending conditions shown in table 4 according to the method of example 1 and vulcanized, and vulcanized rubber sheets were made. The properties of each rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 3. Examples 8, 9, Comparative Examples 16 to 19. A rubber composition was prepared under various blending conditions shown in table 5 according to the method of example 1 and vulcanized, and vulcanized rubber sheets were made. The properties of each rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 4. Examples 10, 11, Comparative Examples 20 to 25. A rubber composition was prepared under various blending conditions shown in table 6 according to the method of example 1 and vulcanized, and vulcanized rubber sheets were made. The properties of each rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 5. Examples 12-15, Comparative Example 26. A rubber composition was prepared under various blending conditions shown in table 6 according to the method of example 1, except using the oil-extended copolymer rubber (4) [40 parts by weight of parafin processing oil per 100 parts by weight of ethylene-propylene-ENB copolymer rubber which has an intrinsic viscosity [η] of 3.2 dl/g measured at 70°C in xylene, an ethylene/propylene ratio of 79/21 and an ENB ratio of 1.3 mole % was blended and Mooney viscosity ML 1 + 4 121°C was adjusted to 93 ), instead of the oil-extended copolymer rubber (1), and vulcanized, and vulcanized rubber sheets were made. The properties of the rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 6. Examples 16,17, Comparative Example 27. A rubber composition was prepared under various blending conditions shown in table 6 according to the method of example 1, except using the oil-extended copolymer rubber (5) (50 parts by weight of parafin processing oil per 100 parts by weight of ethylene-propylene-ENB copolymer rubber which has an intrinsic viscosity [η] of 3.3 dl/g measured at 70°C in xylene, an ethylene/propylene ratio of 70/30 and an ENB ratio of 1.2 mole % was blended and Mooney viscosity ML 1 + 4 121°C was adjusted as 81 ), instead of the oil-extended copolymer rubber (1), and vulcanized, and vulcanized rubber sheets were made. The properties of the rubber composition and the characteristics of the vulcanized rubber sheets are shown in table 6. An annotation: In every above-mentioned table, the blending amount of each component of the rubber composition and the blending prescription of the vulcanizers indicates part by weight. *1: The low-viscosity ethylene-propylene-ENB copolymer rubber having an intrinsic viscosity [η] of 0.33 dl/g measured at 30 °C in toluene, an ethylene/propylene mole ratio of 49/51, and an ENB ratio of 1.3 mole %. *2: The mixture of 1 part by weight of antioxidant Sumilizer MB ( manufactured by Sumitomo Chemical Company Ltd. ) and 0.25 parts by weight of Antigene RD ( manufactured by Sumitomo Chemical Company Ltd. ). *3: The liquid polyisoprene (TL-20 manufactured by Kuraray Company Ltd. ) having a melt viscosity of 70 Pa·s (700 poises) at 25°C. *4: The liquid polyisoprene (Kuraprene LIR-30 manufactured by Kuraray Company Ltd.) having a melt viscosity of 150 Pa·s (1500 poises) at 25°C. *5: The liquid polyisoprene (Kuraprene LIR-506 manufactured by Kuraray Company Ltd.) having a melt viscosity of 360 Pa·s (3600 poises) at 25°C. *6: The liquid polyisoprene (Kuraprene LIR-410 manufactured by Kuraray Company Ltd.) having a melt viscosity of 510 Pa·s (5100 poises) at 25°C. *7: The liquid polyisoprene (Kuraprene LIR-290 manufactured by Kuraray Company Ltd.) wherein 90% of the double bonds are hydrogenated, having a melt viscosity of 3800 Pa·s (38000 poises) at 25°C. Example Comparative Example 1 2 1 2 3 4 5 6 Rubber composition Oil-extended copolymer rubber (1) 140 140 140 140 140 140 140 140 Zinc oxide 5 5 5 5 5 5 5 5 Stearic acid 1 1 1 1 1 1 1 1 FEF-carbon black 70 70 70 70 70 70 70 70 Paraffin processing oil 20 20 20 20 20 20 20 20 NISSEKI Polybutadiene B3000 10 15 10 15 Low viscosity ethylene-propylene-ENB copolymer rubber *1 10 15 Blending prescription of vulcanizers Sunperox DCP-98 5 5 5 5 5 Sulfur 0.3 0.3 0.3 1 1 1 0.3 0.3 Soxinol BZ 1.5 1.5 1.5 Soxinol TT 0.8 0.8 0.8 Soxinol M 0.5 0.5 0.5 Property Rubber composition · Processability ○ ○ × × ○ ○ ○ ○ · Skin condition of sheet ○ ○ × × ○ ○ ○ ○ Vulcanized rubber sheet · Dynamic spring constant 1.8 1.8 2.1 2.3 3.2 3.4 2.2 2.2 · Compression set (%) 11 10 14 48 67 73 14 14 · Durability (10000 cycles) 23.2 30.8 15.4 5.4 >50 >50 22.9 38.8 Example Comparative Example 3 4 5 6 7 8 Rubber composition Oil-extended copolymer rubber (1) 140 140 140 Oil-extended copolymer rubber (2) 140 140 140 Zinc oxide 5 5 5 5 5 5 Stearic acid 1 1 1 1 1 1 MAF-carbon black 50 50 50 50 50 50 NISSEKI Polybutadiene B3000 10 15 10 15 Blending prescription of vulcanizers Sunperox DCP-98 3 3 3 3 3 3 Sulfur 0.2 0.2 0.2 0.2 0.2 0.2 Property Rubber composition · Processability ○ ○ ○ ○ × × · Skin condition of sheet ○ ○ ○ ○ × × Vulcanized rubber sheet · Dynamic spring constant 1.7 1.6 1.8 1.8 1.9 2.0 · Compression set (%) 12 11 13 12 14 15 Comparative Example Example 7 Comparative Example 9 10 11 12 13 14 15 Rubber composition Oil-extended copolymer rubber (1) 140 140 140 140 140 140 Oil-extended copolymer rubber (3) 140 140 Zinc oxide 5 5 5 5 5 5 5 5 Stearic acid 1 1 1 1 1 1 1 1 MAF-carbon black 70 70 70 70 70 70 70 70 Paraffin processing oil 20 20 20 20 20 20 20 20 NISSEKI Polybutadiene B3000 10 3 25 10 10 Blending prescription of vulcanizers Sunperox DCP-98 5 5 5 5 3 3 Sulfur 0.3 0.3 0.3 0.3 0.2 0.2 3 3 Soxinol BZ 1.5 1.5 Soxinol TT 0.8 0.8 Soxinol M 0.5 0.5 Property Rubber composition · Processability ○ ○ × ○ ○ × × ○ · Skin condition of sheet ○ ○ × ○ ○ × × ○ Vulcanized rubber sheet · Dynamic spring constant 2.2 2.1 2.0 2.1 1.8 2.0 1.5 2.0 · Compression set (%) 15 11 12 10 14 18 65 48 · Durability (10000 cycles) 9.5 29.9 11.1 12.6 26.3 9.2 0.1 45.8 Example Comparative Example 8 9 16 17 18 19 Rubber composition Oil-extended copolymer rubber (1) 140 140 140 140 140 140 Zinc oxide 5 5 5 5 5 5 Stearic acid 1 1 1 1 1 1 FEF-carbon black 60 60 60 60 60 60 Paraffin processing oil 10 10 10 10 10 10 Antioxidant *2 1.25 1.25 1.25 1.25 1.25 1.25 Liquid polyisoprene 1 *3 10 Liquid polyisoprene 2 *4 10 Liquid polyisoprene 3 *5 10 Liquid polyisoprene 4 *6 10 Liquid polyisoprene 5 *7 10 Blending prescription of vulcanizers Sunperox DCP-98 3 3 3 3 3 3 Sulfur 0.2 0.2 0.2 0.2 0.2 0.2 Property Rubber composition · Processability ○ ○ × × × ○ · Skin condition of sheet ○ ○ × × × ○ Vulcanized rubber sheet · Dynamic spring constant 1.7 1.7 1.9 2.0 2.0 2.0 · Compression set (%) 20 20 21 24 25 24 · Durability (10000 cycles) >50 >50 14.3 - - - Example Comparative Example 10 11 20 21 22 23 24 25 Rubber composition Oil-extended copolymer rubber (1) 140 140 140 140 140 140 140 140 Zinc oxide 5 5 5 5 5 5 5 5 Stearic acid 1 1 1 1 1 1 1 1 FEF-carbon black 60 60 60 60 60 60 60 60 Paraffin processing oil 10 10 10 10 10 10 10 10 Liquid Polyisoprene 2 *4 8 12 24 8 12 24 Blending prescription of vulcanizers Sunperox DCP-98 3 3 3 3 Sulfur 0.2 0.2 0.2 0.2 1 1 1 1 Soxinol BZ 1.5 1.5 1.5 1.5 Soxinol TT 0.8 0.8 0.8 0.8 Soxinol M 0.5 0.5 0.5 0.5 Property Rubber composition · Processability ○ ○ × ○ × ○ ○ ○ · Skin condition of sheet ○ ○ × ○ × ○ ○ ○ Vulcanized rubber sheet · Dynamic spring constant 1.7 1.7 1.9 1.9 1.7 2.3 2.4 2.8 · Compression set (%) 18 20 17 21 52 59 71 81 Example Comparative Example Example 12 13 14 15 26 27 16 17 Rubber composition Oil-extended copolymer rubber(4) 140 140 140 140 140 Oil-extended copolymer rubber(5) 150 150 150 Zinc oxide 5 5 5 5 5 5 5 5 Stearic acid 1 1 1 1 1 1 1 1 FEF-carbon black 40 40 40 40 40 60 60 60 Paraffin processing oil 10 10 10 Antioxidant 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 NISSEKI Polybutadiene B3000 5 10 15 20 10 15 Blending prescription of vulcanizers Sunperox DCP-98 3.5 3.5 3.5 3.5 3.5 5 5 5 Sulfur 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.3 Property Rubber composition · Processability ○ ○ ○ ○ × × ○ ○ · Skin condition of sheet ○ ○ ○ ○ × × ○ ○ Vulcanized rubber sheet · Dynamic spring constant 1.6 1.6 1.5 1.6 1.8 1.8 1.6 1.6 · Compression set (%) 13 12 12 12 16 17 15 14

Claims: A vulcanized rubber obtainable by vulcanizing a composition comprising: (A) 110-175 parts by weight of an oil-extended copolymer comprising 100 parts by weight of an ethylene-α-olefin-non-conjugated diene copolymer rubber with an intrinsic viscosity [η] of 3 dl/g or more and 10-75 parts by weight of an extender oil; (B) 5-20 parts by weight of a liquid diene polymer with a melt viscosity of 10-300 Pa·s (100-3000 poises) at 25°C, per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber; and (C) 10-80 parts by weight of a reinforcing filler, per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber; with an organic peroxide. The vulcanized rubber according to Claim 1, wherein the melt viscosity of the liquid diene polymer is 20-150 Pa·s (200-1500 poises) at 25°C. The vulcanized rubber according to Claim 1 or 2, wherein the iodine value of the liquid diene polymer is greater than 300 and less than 600. The vulcanized rubber according to any one of Claims 1 to 3, wherein the liquid diene polymer is a liquid polybutadiene or a liquid polyisoprene. The vulcanized rubber according to any one of Claims 1 to 4, wherein the organic peroxide is selected from dicumyl peroxide, di-tert butyl peroxide, tert-butyl cumylperoxide 1,1-di(tert-butyl peroxy)-3,3,5-trimethylcyclohexane, benzoylperoxide and lauroylperoxide. The vulcanized rubber according to any one of Claims 1 to 5, wherein the amount of the organic peroxide is 0.5-10 parts by weight per 100 parts by weight of the ethylene-α-olefin non conjugated diene copolymer rubber. The vulcanized rubber according to any one of Claims 1 to 6, wherein the amount of the reinforcing filler is 30-70 parts by weight per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber. The vulcanized rubber according to any one of Claims 1 to 7, wherein the reinforcing filler is carbon black. The vulcanized rubber according to any one of Claims 1 to 8, wherein the amount of the extender oil is 30-75 parts by weight per 100 parts by weight of the ethylene-α-olefin-non-conjugated diene copolymer rubber. Use of the vulcanized rubber according to any one of Claims 1 to 9 for the production of heat resistant vibration-isolators. Vibration-isolator comprising a vulcanized rubber according to any one of Claims 1 to 9.

Inventors: AOSHIMA MASASHI, NAKATA HIROKI, SATO MITSUHIKO, AOSHIMA, MASASHI, NAKATA, HIROKI, SATO, MITSUHIKO
Applicants: SUMITOMO CHEMICAL CO, SUMITOMO CHEMICAL COMPANY LIMITED
Application year: 1994
Main classification: C08L23
IPC codes: C08J3, C08K5, C08K3, C08L23